A device and method is shown and described for use in irradiating or otherwise administering light to a location within the body of a patient and, more particularly, a device and method for the use of photodynamic therapy for the therapeutic treatment of tissue in the brain or other part of the body of the patient, including tumors, such as malignant brain neoplasms.
There are a variety of medical procedures that require light or irradiated energy to be administered to a patient within the body. Photodynamic therapy (PDT) is a form of treatment that relies on exposing an area of tissue to a selected wavelength of activating radiation. PDT uses non-toxic, photosensitive compounds that accumulate selectively in targeted tissue. The photosensitive compounds become toxic when exposed to light at selected wavelengths. This leads to chemical destruction of any tissues which have selectively taken up the photosensitizer and have been selectively exposed to light.
One application of PDT is in oncology for the destruction of malignant cell masses in the body. PDT has been used effectively in the treatment of a variety of human tumors and precancerous conditions, including basal and squamous cells, skin cancers, lung cancer, breast cancer, metastatic to skin, brain tumors, and head and neck, stomach, and the female genital tract malignancies. PDT has also been used to treat the cancers and precancerous conditions of the esophagus, such as Barrett's esophagus. In the latter application, a photosensitizer, such as Photophrin, is first administered. A 630 nm light from a KTP/dye laser, a diode laser, or an argon-pumped dye-laser is delivered using a PDT balloon having a reflective inner surface. The PDT balloon includes an internal cylindrical diffuser and has several windows for illuminating the treatment area.
Therapeutic use of PDT in the brain has been minimal Therefore, evidence for the efficacy and the safety of PDT for use in the brain is limited in quality and quantity. However, the introduction of probes or similar devices into the brain is common in many surgical procedures. The probes used for intracranial penetration are typically fabricated so that their introduction into the brain is as minimally traumatic as possible. During typical implantation, a surgeon feeds the probe into the brain through an aperture in the skull. Probes inserted into the brain typically include ports for drug delivery or paired contacts positioned at specific points or regions in the brain. The contacts are electrical, chemical, electrochemical, temperature or pressure contacts, which enable the observation and analysis of the brain state or provide stimulation. In addition, neurosurgeons use photosensitizers when resecting infiltrative tumors. The photosensitizers fluoresce when light of a certain wavelength is shined on the cells allowing for rough identification of the tumor margins.
For the foregoing reasons, there is a need for a new device and method for the use of photodynamic therapy (PDT) for the therapeutic treatment of tissue in the brain of a patient. The new device and method should ideally include a probe or similar device familiar to neurosurgeons to deliver PDT for the treatment of the brain tissue, including tumors such as malignant brain neoplasms. In one aspect, the new device and method for PDT is useful and effective for other parts of the body in addition to the brain.